From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:13925 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752429AbdBUOzH (ORCPT ); Tue, 21 Feb 2017 09:55:07 -0500 MIME-version: 1.0 Content-type: text/plain; charset=utf-8; format=flowed Subject: Re: [PATCH] dma-buf: add support for compat ioctl To: =?UTF-8?Q?Christian_K=c3=b6nig?= , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, Bartlomiej Zolnierkiewicz From: Marek Szyprowski Message-id: Date: Tue, 21 Feb 2017 15:55:02 +0100 In-reply-to: Content-transfer-encoding: 8bit References: <1487683261-2655-1-git-send-email-m.szyprowski@samsung.com> <917aff70-64f7-7224-a015-0e77951bbc1d@vodafone.de> Sender: linux-media-owner@vger.kernel.org List-ID: Dear All, On 2017-02-21 15:37, Marek Szyprowski wrote: > Hi Christian, > > On 2017-02-21 14:59, Christian König wrote: >> Am 21.02.2017 um 14:21 schrieb Marek Szyprowski: >>> Add compat ioctl support to dma-buf. This lets one to use >>> DMA_BUF_IOCTL_SYNC >>> ioctl from 32bit application on 64bit kernel. Data structures for >>> both 32 >>> and 64bit modes are same, so there is no need for additional >>> translation >>> layer. >> >> Well I might be wrong, but IIRC compat_ioctl was just optional and if >> not specified unlocked_ioctl was called instead. >> >> If that is true your patch wouldn't have any effect at all. > > Well, then why I got -ENOTTY in the 32bit test app for this ioctl on > 64bit ARM64 kernel without this patch? > I've checked in fs/compat_ioctl.c, I see no fallback in COMPAT_SYSCALL_DEFINE3, so one has to provide compat_ioctl callback to have ioctl working with 32bit apps. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland